what gears do you have now? must be fairly low
and what rpm do you want to turn at say 65mph?
the gears you stated are gonna give the rpms your saying are to high..
3.73-33.5-1:1-65mph=2432rpm
4.11-33.5-1:1-65mph=2679rpm
I would look more towards a od trans with a lower axle ratio to get the best of both worlds
hers the calc I use ..just fill in blanks at bottom of the page..
http://www.csgnetwork.com/multirpmcalc.html